Unable to use node labels to schedule vttablet pods.

[bluecrabs007]

Currently, the operator uses a standard NodeSelector topology.kubernetes.io/zone which is exposed via the spec.Zone in the VitessCluster custom resource.
This means, the vttablets' pod spec's nodeSelector can only specify a label, such as, topology.kubernetes.io/zone=<value> and nothing else. Reference
For usecases where we want to direct the VTOP to schedule the vttablets onto nodes that have a specific label, for example hardware=intel, this is currently not possible.

Would be nice if the operator exposes a way to pass arbitary set of labels via the VTTablet's nodeSelector
https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#nodeselector

[GenLN]

but you can use affinity inside tablet pools like

keyspaces:
- name: keyspace1
  ....
  partitionings:
  - equal:
      parts: 2
      shardTemplate:
        databaseInitScriptSecret:
          name: init
          key: init_db.sql
        tabletPools:
        - cell: cellName
          affinity:
            podAntiAffinity:
            nodeAffinity:
          type: replica
          replicas: 3
          ....

[mattlord]

@bluecrabs007 Are there reasons why you cannot or would not want to use the affinity options that @GenLN mentioned?

Generally these allow you to do what you can do with nodeSelector's and then some: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#affinity-and-anti-affinity

If there's some feature gap here then we could of course add nodeSelectors as well, but I'm not aware of what those might be. Thanks!